Good form: Strengthen and stretch with these variations

This is a challenging exercise to strengthen the muscles in your abs, arms and legs while simultaneously stretching your abs, hips and quadriceps. Make sure you move slowly, and focus on holding your balance while moving from one variation to the other. It's best to do this once you are warmed up.

1. Begin on all fours on a yoga mat with your hands under your shoulders (fingers facing forward) and your knees under your hips. Straighten your right leg out and slowly shift your weight to your left hand and knee as you pivot your shoulders, chest and hips to the right. Place your right hand behind your head and raise your right foot up to hip level. Keep your right toes and knee facing out to the right. Turn your gaze upward if possible. Pause for a few breaths while maintaining your balance. Once you feel stable, move to the next variation.

2. Keeping your right leg lifted, bend your knee and grasp the top of your right foot with your right hand. Pause, focus on maintaining your balance, then bring your right heel close to your right buttock. Move your right knee slightly back so it is line with your hips. Be sure your right shoulder stays above your right hand. You will feel a strong stretch in the front of your right thigh. Now, move your tailbone in toward your body, press your hips forward and arch your spine as you push your right foot away from your hips to bring a strong stretch in the front of your torso. Hold this pose for three to six breaths, then release your foot, return to all fours and repeat on the other side.

Voight is the creator of a line of fitness DVDs, including "Full Body Stretch" and "Ballet BodySculpt."